<!doctype html>
<html lang="en"> <head>
       <meta charset="UTF-8">
       <meta name="viewport"
             content="width=device-width, user-scalable=no, initialscale=1.0, maximum-scale=1.0, minimum-scale=1.0">
       <meta http-equiv="X-UA-Compatible" content="ie=edge">
       <script src="js/jquery.min.js"></script>
       <title>Document</title>
    <script>
        // ajax 提交
        function mysub() {
            // 1.判空
            var username = jQuery("#username");
            var password = jQuery("#password");
            if(jQuery.trim(username.val())=="") {  //trim是用来去空格的
                alert("请先输入用户名！");
                return;
            }
            jQuery.ajax({
                url:"/user/login2",
                type:"POST",
                data:{"username":username.val(),"password":password.val()},
                success:function (result) {
                    alert(result);
                }
            });

        }
    </script>
</head>
<body>
   <div style="text-align: center;">
           <h1>登录</h1>
          ⽤户：<input id="username">
           <br>
          密码：<input id="password" type="password">
           <br>
           <input type="button" value=" 提交 " onclick="mysub()"
                  style="margin-top: 20px;margin-left: 50px;">
       </div>
</body>
</html>